Concepts presented herein relate to rotary-type surgical cutting tools and powered handpieces. More particularly, it relates to rotary surgical cutting tools providing robust driven connection with a powered handpiece.
Powered surgical handpieces are commonly used in many medical specialties to drive surgical tools. For example, powered surgical handpieces are used to drive surgical drills, blades or other cutting tools in performing various diverse cutting-type functions including drilling, tapping, resection, dissection, debridement, shaving, pulverizing, and shaping of anatomical tissue including bone. The handpieces are typically configured for selective coupling to, and driving of, a variety of different rotary-type surgical cutting instruments that are each designed to perform a specific procedure. During use, based upon the specific surgical procedure, the surgeon selects the appropriate surgical tool and mounts it to the powered handpiece. The powered handpiece is then operated to move (e.g., rotation, oscillation) the tool in performing the surgical procedure. Additional procedural steps can later be performed by mounting a differently-styled tool to the same powered handpiece.
The improved capabilities of powered surgical handpieces, as well as the vast number of surgical cutting tools now available, have undoubtedly greatly increased the number of neurological, spine, ENT/head/neck and other procedures that a surgeon can perform utilizing a single surgical system (i.e., a single powered handpiece with multiple surgical cutting tools). Selective driven coupling between the powered handpiece and each tool is typically effectuated within a housing of the handpiece. The housing carries an internal drive chuck configured to receive a shank of the surgical cutting tool in a mating fashion. Thus, the shank of each surgical cutting tool useful with a particular handpiece has a common shape, with this shape corresponding to the handpiece drive chuck (e.g., circular, hexagonal). The drive chuck is connected to (or formed as part of) a drive shaft; upon connection of the surgical cutting tool to the drive chuck, powered rotation of the drive shaft rotates the cutting tool.
In current approaches, the cutting tool, including the shank, is generally shaped as an elongated cylinder defining a single central axis about which the tool is rotated during use. The handpiece drive chuck forms a corresponding, generally cylindrical-shaped passage for receiving the shank, effectuating a coupled connection and subsequent driven interface at point contacts created solely about the single central axis. The shank (or other regions of the cutting tool) may include recesses, grooves, or other features deviating from a truly cylindrical shape for purposes of effectuating an axial and/or rotational lock relative to the drive chuck. In some situations, complex machining/grinding can be required to achieve the requisite torque transmission and axial retention features, resulting in high contact stresses and reduced interface stiffness. These potential concerns, in turn, may lead to reliability issues, such as premature tool and/or handpiece failure. In other instances, alignment of the shank and drive chuck can be problematic, leading to user frustration.